Step 7: Fixed voltmeter

Step 8: Power and debugging

Double-check the circuit again before power on it. Make sure there is no any short current between IC pins. Check whether connection between component...

I’ll show you how I made the step-down DCDC converter on the FlowerPad-NoPlated protoboard, and finally power a 5W HB LED.
The DCDC itself is nothing we haven’t seen before, but the construction of this thing is amazing. The entire build is on the NoPlated ProtoBoard, meaning there are no wires at all.

This converter based on MP2307. This device integrates 100mOHM MOSFETS that provide3Aof continuous load current over a wide operating input voltage of 4.75V to 23V. I used a 12V DC dapter as input in this converter. So the output can be adjusted from 1.2V to 10V by a 10Mohm potentiometer. One voltage meter is fixed for real time voltag display. It is a good tool in electronic DIY. Now, please follow my step to starting your DIY.

Step 2: Soldering the MP2307

The red marking numbers shown connectivity between the SOIC pad and Flower pad. Non-plated pad design make pads on different layer is independent. Please note that the SOIC pad connect with bottom layer flower pad. You need to make via if you want to connect top and bottom layer pad. The method will be mentioned below.

Step 3: Fixed DC connectorï¼J3ï¼

The above picture is diagram of the electronic connections. Please fix the J3 connector as shown in the picture. The connector pin is flat, so you need to drill two larger holes as following picture shown.

Step 4: Wiring on double side use solder

We recommend the left soldering copper when‘make a bridge between two pads’ use solder.

Refer the diagram to wire on double side. Please note that the red line indicatet top layer traceï¼and blue line indicate bottom layer trace.

As the following picture shown, move the soldering copper in horizont direction to disconnect two padsï¼and move in vertical to connect. Please measure whether the trace is conduction when you complete it every time. It will increase your success rate.

Step 5: Making via on Flower protoboard, connect top and bottom pad.

We need make 4 vias on this board. At first, bend a metal wire as picture1 shown. The meatl wire can be LED’s leg or other things your can find easily. Then solder it on top layer. Thirdlyï¼solder it on bottom layer.

You must fast enough to solder bottom layerï¼otherwise you may dissolve top layer solder.

Step 6: Making your connector solder more reliable.

Connectors usually need to be able to withstand multiple – plug. It means we need to solder it more reliable. As following picture shown, use a knife to scratch the black solder mask. You can see a square shape pad.

It has more solder area than primary Flower pad. Larger soldered dot have more soldering intensity.

Step 7: Fixed voltmeter

The voltmeter has a wide voltage measurement range from 3.2 to 30V. Two mounting holes make you can fix it onto Flower board easily.

The red line connect to output anode, and the black connect to cathode.

Step 8: Power and debugging

Double-check the circuit again before power on it. Make sure there is no any short current between IC pins. Check whether connection between components is reliable. ã

Finallyï¼ confirm the input and output poles is no short circuit. Power on the converter then rotate the potentiometerï¼you can adjust the output voltage, and the voltage display on voltmeter.

I use this DCDC converter to power a 5W HB LED over 30 hours. As the tested result, it works stable and reliable.

Fair point - I only looked through very briefly before posting my original comment. What I meant was that I didn't know that for a hobbyist/amateur there was a simple way to make an adjustable buck converter, and for the DIY'er the circuit is an efficient alternative to linear PSU's, so to me from that perspective it looks great. I didn't look at the prices of any of the parts. Following on from your other comment I had a look on eBay for "MP2307" and found lots of converter modules using the chip going pretty cheap, but not the chips themselves. Digital panel voltmeter modules are pretty cheap too.

I like the flowerboard because it looks like a good way to make prototypes using smd's - and since my main source of components is from scrap, I have an increasing number of these. It doesn't look to be available in the UK though.

As you say though, now I've looked more closely, it does have a spammy feel.

It should be noted that in the parts list, "some capacities and some capacities" actually means 4 resistors, 1 inductor, 2 electrolytic capacitors, and 3 (usually film or ceramic type) capacitors.

It is a fair project to build, but it also feels a little like spam since this project was developed for the Elecfreaks website, posted there, posted here by a member named Elecfreaks, and uses not one or two but links four products Elecfreaks sells.

Lastly, it seems the total cost for this project, including ordering the other (more) parts elsewhere and shipping for everything, will slightly exceed $30 USD. That's quite a lot to pay for a low current power supply subcircuit (still needing to supply input power and support parts to do so), I'm fairly confident people could buy something equivalent or higher in functionality for half the cost if not less on eBay, probably even already built.

On a side note, if they are going to sell these protoboards which can't easily be sawed down to the smaller size because of the multi-layer design which could short out as a result, it would at least be good if Elecfreaks sourced and sold project cases that were an exact fit as there are many situations where an application calls for a little bit of protection for the construction instead of only a bare circuit board with components on it.

Your design is a voltage regulator which mostly works for this application. Far superior would be a current regulator as LED's are current-driven devices. The problem I foresee is that as time passes or temperature changes the LED's operating voltage will vary slightly.

Let's say it is running happily at 5 watts at 3.7 volts today. At that point on the voltage/current curve, it would need to draw about 1.3A. At 3.8 volts, the current draw may be 2.5 amps, though — 9.5 watts. If the LED's voltage characteristics changed slightly (i.e. the 3.8 volt/2.5 amp point "slid down" to 3.7 volts but still 2.5 amps) — which they do over time or with changing temperature — then your supply would stay at 3.7 volts but now supply 2.5 amps and burn out the LED.